The datasheet is INCORRECT! but your understanding is not so far off...
The battery capacity of 7Ah, x its voltage (12V), indicates its stored energy not power. If you need 7A for 1 hour you need to read the fine print, to see if that was the capacity at its "1C" rate (1x its capacity, or drain it in an hour)
Oh wait, there is no fine print on that page, unlike a proper datasheet. So if you need that current you take your chances or look elsewhere.
The Yuasa datasheet shows 7Ah at the 20hour rate, falling to 6.4Ah at the 10 hour rate. So that battery from a reputable manufacturer is rated to last 20 hours at 350ma, falling to 10 hours at only 640 ma. It also tells you that the endpoint they measured to is 1.75V per cell, or 10.5V. But at least it tells you what you're getting.
Lead acid batteries can be tuned for different purposes including high current, so it's possible that the advertised battery will source 7A for 1 hour ... if the vendor is trustworthy. If they are, they may be able to supply a proper datasheet on request. Can't hurt to ask!
Very sparse data on that controller... When the windmill generates a too high output the controller will apply the brake. This might be a dump resistance or some other smarter load that leaves power for the utility. It doesn't say on this particular controller how it is done. There is a hysteresis that releases the brake when the voltage reaches 13.5V.
Best Answer
It means that the battery has a capacity of 25 Ah when discharged in 10 hours. 25 Ah is 25 Amps for 1 Hour which is equivalent to 2.5 Amps in 10 Hours.
So if you load the battery with 2.5 Amps it will last 10 Hours.
If loaded with a higher current usually battery capacity decreases so that is why the 10 Hours is mentioned, it results in a higher battery capacity making the battery look "better".
How many watts: simple 2.5 Amps x 12 V = 30 Watts and that for 10 Hours.